MO818: PTH Levels and Mortality in Incident Haemodialysis Patients

Abstract

Abstract BACKGROUND AND AIMS Serum intact parathyroid hormone (iPTH) is associated with the prognosis of haemodialysis (HD) patients; however, its optimal range for reducing mortality remains unknown. The aim of this study was to assess the association between different serum iPTH levels and mortality in incident HD patients. METHOD We conducted a retrospective single-centre study of incident HD patients between January 2013 and 2020. According to the iPTH level measured at baseline, patients were categorized into four groups: <150 pg/mL, 150–300 pg/mL, 301–600 pg/mL and >600 pg/mL. Clinical, analytical and demographic data were compared among groups. All-cause mortality over a mean follow-up of 3.2 years was assessed using standard survival methods. Statistical analysis was performed using SPSS (Version 23 for Mac OSX). RESULTS The mean age of 149 patients was 74.14 ± 14.17 years, 95 (63.8%) were male, 75 (50.3%) were diabetic, 85 (57%) had congestive heart failure (CHF) and 110 (73.9%) had hypertension. A total of 46 patients (30.9%) were treated with vitamin D analogues, 2 (1.3%) with calcimimetics and 25 (16.8%) with oral phosphate binders. A total of 57 (38.3%) patients had iPTH < 150 pg/mL, 44 (29.5%) 150–300 pg/mL, 35 (23.5%) 301–600 pg/mL and 13 (8.7%) > 600 pg/mL. There were no age, gender, comorbidity or HD modality differences among groups. Patients with iPTH < 150 pg/mL had higher c-reactive protein (CRP) (P = .042), higher serum bicarbonate (P = .020), lower albumin (P = .001), lower serum phosphate (P = .009) and lower bone-specific alkaline phosphatase (BAP) (P = .008). During the study follow-up period, 82 patients (55%) died. Multivariate Cox regression showed that patients with iPTH < 150 pg/mL had an increased risk of all-cause mortality when compared with those with iPTH 301–600 pg/mL {HR: 0.59, [95% confidence interval (95% CI) 0.36–0.96]; P = .035} and iPTH > 600 pg/mL [HR: 0.36, 95% CI 0.19–0.70; P = .02] in both unadjusted and adjusted models for age, albumin, diabetes, CHF and hypertension. No significant difference was found between iPTH < 150 pg/mL and iPTH 150–300 pg/mL groups. When the reference was changed to iPTH > 600 pg/mL, patients in this group had a decreased mortality risk when compared with those with iPTH < 150 pg/mL (HR: 2.75, 95% CI 1.43–5.29; P = .02) and iPTH 150–300 pg/mL (HR: 2.23, 95% CI 1.14–4.36; P = .02), but not iPTH 300–600 pg/mL. CONCLUSION In our study, the baseline iPTH level was associated with all-cause mortality in incident HD patients. Our results suggest that the optimal serum iPTH level conferring the lowest mortality risk is > 300 pg/mL in this group of patients.